Force system evaluation of symmetrical beta-titanium T-loop springs preactivated by curvature and concentrated bends

Introduction The objective of this research was to compare the effect of preactivation on the force system of beta-titanium T-loop springs (TLSs). Methods Twenty TLSs with dimensions of 6 × 10 mm, of 0.017 × 0.025-in beta-titanium alloy, were randomly divided into 2 groups according to their preacti...

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Published in:American journal of orthodontics and dentofacial orthopedics 2011-08, Vol.140 (2), p.e53-e58
Main Authors: Caldas, Sergei Godeiro Fernandes Rabelo, Martins, Renato Parsekian, Galvão, Marília Regalado, Vieira, Camilla Ivini Viana, Martins, Lídia Parsekian
Format: Article
Language:English
Subjects:
Dental Alloys
Dental Stress Analysis
Dentistry
Materials Testing
Orthodontic Appliance Design
Orthodontic Space Closure - instrumentation
Orthodontic Wires
Random Allocation
Stress, Mechanical
Titanium
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Summary:Introduction The objective of this research was to compare the effect of preactivation on the force system of beta-titanium T-loop springs (TLSs). Methods Twenty TLSs with dimensions of 6 × 10 mm, of 0.017 × 0.025-in beta-titanium alloy, were randomly divided into 2 groups according to their preactivation. By using a moment transducer coupled to a digital extensometer indicator adapted to a testing machine, the amounts of horizontal force and moment produced were recorded at every 0.5 mm of deactivation from 5 mm of the initial activation in an interbracket distance of 23 mm. The moment-to-force ratio, the “neutral position” and the load-deflection ratio were also calculated. Results TLSs preactivated by curvature delivered horizontal forces significantly lower than those preactivated by concentrated bends. No differences were found in relation to the moments produced throughout the deactivation of both groups. The moment-to-force ratios were systematically higher on the TLSs preactivated by curvature than those preactivated by concentrated bends, except on 5 mm of activation. Significant differences were found in the load-deflection rates and “neutral position.” Conclusions The TLSs preactivated by curvature delivered lower horizontal forces and higher moment-to-force and load-deflection ratios than did those preactivated by concentrated bends.
ISSN:0889-5406
1097-6752
DOI:10.1016/j.ajodo.2010.11.022